The present invention relates to dental tools and in particular dental tools capable of releasable attachment to an automatic tool driver.
A conventional dental tool assembly is disposable and comprises a dental tool such as a pin, drill, burr or reamer which is fixed to, or forms an integral part of, a tool holder. The tool holder may be provided with a latching groove or other suitable means for engagement with the driving mechanism of a dental tool driver designed to rotate the entire assembly at variable speed.
The dental tool driver has a size such that it can be held and operated manually, whereas the dental tool holder is usually very small, only a few centimetres long. The dental tool driver conventionally has a combined latching and driving mechanism into which the end of the dental tool holder is fitted.
The combined latching and driving mechanism includes a substantially flat (or otherwise appropriately shaped) driving surface which engages with a correspondingly shaped (usually flat) mating, surface at one side of the end of the driver. The driving surface rotates around the axis of the holder and thereby rotates the holder and the dental tool fixed in it. The latching and driving mechanism also has a latch which engages within a groove in the holder transverse to the axis of the holder whereby the holder is held in position so that the driving surface can drive the driven surface without any risk of the holder falling out of the latching and driving mechanism. This arrangement is conventional and is widely used in dental apparatus.
Usually, the dental tool is formed separately from the holder using conventional metal cutting techniques and is subsequently attached to the tool holder. Suitable materials for manufacturing dental tools include titanium, gold, and special graded stainless tool steels.
The tool holder may be machined from a suitable source of material and is provided with a longitudinal bore at the end distant from the latching groove and into which an extended shank of the dental tool may be inserted. The dental tool is usually fixed within the tool holder either by punching the tool holder to cause a permanent interlocking distortion or by applying a force along the longitudinal axis of the dental tool positioned within the longitudinal bore to permanently concertina the tool shank thereby locking the two together. Alternatively, a plastic tool holder may be moulded around the pre-formed dental tool.
In another production technique the entire tool assembly is machined from a single length of metal material to form the dental tool as an integral part of the tool holder.
A typical production line using the above techniques produces around five tool assemblies per minute. This relatively slow production process means that the unit price for each tool assembly is high.